Any person, male or female, gay or straight, who allows men to cum inside them without properly cleaning between sexual encounters. This allows for more than one person's sperm to be inside them at the same time.

"I screwed that blonde chic last night but her pussy felt all wet and sloppy."
"That's cuz I fucked her just before you did and she still had my cum inside her when you tapped it. Dude, you were fucking a personal sperm bank!"